TECHNICAL FIELD OF THE INVENTION

The invention relates to a heat exchanger comprising two tanks, whereby tubes for medium which is to be cooled/heated are arranged to extend between connection surfaces of the tanks, between which tubes there are ducts for cooling/heating medium which are arranged to run at an angle to the longitudinal direction of the tubes. The invention also relates to the use of such a heat exchanger, e.g. as a cooler, in a motor vehicle.

BACKGROUND

It is desirable to provide a heat exchanger with a maximum effective heat transfer area. Achieving a larger such area has previously entailed increasing the dimensions of the heat exchanger, but it is desirable to achieve this increase in effective area without increasing the overall dimensions of the heat exchanger.

Particularly in the vehicle industry, available space for a heat exchanger in the front of the vehicle is extremely limited. In the case of a truck, the space is often limited upwards by the cab and sideways and downwards by, for example, various frames and members. To accommodate a larger heat exchanger, the vehicle has quite simply to be made larger, which is not only more expensive but also leads to a bulkier vehicle, which is undesirable for several reasons, e.g. rules on maximum sizes of vehicles, or shortage of space at places where the vehicle is likely to operate.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a heat exchanger with increased effective heat transfer area while maintaining the same overall dimensions. This is achieved by a heat exchanger comprising two tanks, whereby tubes for medium which is to be cooled/heated are arranged to extend between connection surfaces of the tanks, between which tubes there are ducts for cooling/heating medium which are arranged to run at an angle to the longitudinal direction of the tubes, said connection surfaces being arranged to converge in the direction of flow of the cooling/heating medium.

The result as viewed in the direction of flow of the cooling/heating medium is increased upstream area of the heat exchanger, i.e. the first area which the cooling/heating medium encounters when it reaches the heat exchanger. This area is most effective with regard to heat transfer, since the temperature difference between the cooling/heating medium and the medium which is to be cooled/heated is greatest precisely when the cooling/heating medium reaches the aperture to the heat exchanger's ducts for the cooling/heating medium. Increasing the most effective area for heat transfer makes it possible to increase the cooling/heating capacity of the heat exchanger while maintaining the same overall dimensions.

The connection surfaces are preferably arranged to converge in such a way that the upstream portion of the tubes, as viewed in the direction of flow of the cooling/heating medium, extends across, in principle, the whole width of the heat exchanger, and in such a way that the downstream portion of the tubes, as viewed in the direction of flow of the cooling/heating medium, extends across a portion of the width of the cooler/heater which allows the tanks to be of sufficient size.

The result is maximum utilisation of the heat exchanger's width for heat transfer while at the same time catering for the necessary size of tanks.

With advantage, the flow ducts in a region close to the respective tanks are angled relative to other flow ducts for the cooling/heating medium, in such a way that the flow ducts in these regions of increasing proximity to the respective connection surface run increasingly parallel with the connection surfaces. Optimum air flow conditions through the heat exchanger can thus be achieved.

To prevent waste in the making of heat exchangers according to the invention, the connection surfaces may with advantage converge at, in principle, an angle of 45° to the longitudinal direction of the tubes.

This makes it easy to use all cut tubes by turning them in different directions, without further machining which would take time and generate unnecessary waste.

The invention also relates to the use of a heat exchanger as above in a motor vehicle. The heat exchanger is particular suitable for use in vehicles, such as trucks, in which space is limited by surrounding components. The heat exchanger can thus be used as, for example, a water cooler, a charge air cooler or as a component of the air conditioning system.

DESCRIPTION OF THE DRAWINGS

The invention is described below with reference to the attached drawings, in which:

- Fig. 1 depicts schematically a heat exchanger according to a preferred embodiment of the invention as viewed from above, - Fig. 2 depicts schematically a heat exchanger according to a preferred embodiment of the invention as viewed from in front, - Fig. 3 is a schematic cross-section from above of a heat exchanger according to a preferred embodiment of the invention, - Fig. 4 is a schematic cross-section from in front of a heat exchanger according to a preferred embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

The heat exchanger 1 comprises two tanks 2, 2'. Tubes 3 for medium to be cooled/heated are arranged to extend between connection surfaces 4, 4' of the tanks 2, 2', and ducts 5 for cooling/heating medium are arranged to run at an angle to the longitudinal direction of the tubes 3. The ducts 5 are made up in a conventional manner of flanges 6 arranged on the tubes 3. The connection surfaces 4, 4' are arranged to converge in the direction of flow of the cooling/heating medium. The direction of flow of the cooling/heating medium is represented in Fig. 1 by an arrow F.

As may be seen in Figs. 1 and 2, the connection surfaces 4, 4' converge in such a way that the upstream portion 7 of the tubes 3, as viewed in the direction of flow of the cooling/heating medium, extend across, in principle, the whole width of the heat exchanger 1, i.e. from a corner 8 of one tank 2 to the corresponding corner 8' of the second tank 2'. The upstream portion 7 is the first portion of the tubes 3 which the cooling/heating medium encounters when it reaches the heat exchanger 1. Depending inter alia on the viscosity and other flow characteristics of the medium which is to be cooled/warmed, more space may be needed at the corners 8, 8', in which case these corners may be made less sharp than in Fig. 1.

The connection surfaces 4, 4' also converge in such a way that the downstream portion 9 of the tubes 3, as viewed in the direction of flow of the cooling/heating medium, extends across a portion of the heat exchanger's width which allows the tanks to be of sufficient size. Sufficient size usually means the tanks being of the same volume which corresponding tanks would have in a heat exchanger which has the same overall dimensions and whose tanks have, in principle, parallel connection surfaces.

In the drawings, the connection surfaces 4, 4' are straight, but there may be applications in which these surfaces have with advantage a different shape, e.g. convex or concave. The design of the tanks 2, 2' may also vary. Their functions include even distribution between the tubes 3 of medium which is to be cooled/heated. The magnitude of their cross-section may therefore be varied in a vertical direction in order to ensure optimum distribution.

As may be seen in Fig. 3, the flow ducts 51 in a region close to the respective tanks 2, 2' are angled relative to other flow ducts 52 for the cooling/heating medium, so that the flow ducts 51 in these regions run increasingly parallel with the connection surface 4, 4' of the respective tank 2, 2' the closer the ducts 51 of the respective tank 2, T are arranged. The other flow ducts 52 run, in principle, perpendicular to the longitudinal direction of the tubes 3.

Fig. 4 depict schematically an embodiment in which the ducts 53, in the region close to the respective tank, do not go all the way from the heat exchanger's upstream side 7 to its downstream side 9, as viewed in the direction of flow of the cooling/heating medium.

The embodiments in Figs. 3 and 4 represent preferred embodiments for enabling the cooling/heating medium to flow through the heat exchanger, i.e. into the ducts 5, 51, 52, 53 on the upstream side 7 of the heat exchanger and out from the ducts 5, 51, 52, 53 on the downstream side of the heat exchanger, with optimum flow conditions.

The connection surfaces 4, 4' preferably converge at, in principle, an angle of 45° to the longitudinal direction of the tubes 3. This makes it possible, during the manufacture of the heat exchanger 1, for the tubes 3 to be cut without unnecessary waste due to offcuts, because it is easy for the tubes 3 whose ends are cut at an angle of 45° to be turned and used above one another in the heat exchanger 1.

Where the heat exchanger takes the form of a water cooler for a vehicle, e.g. a truck, the medium to be cooled is radiator fluid, usually a water/glycol mixture, and the cooling medium is ambient air which flows into the ducts 5 when the vehicle is in motion or when the vehicle's fan is running. The radiator fluid flows into the one tank 2 via the inlet 10 and out from the second tank 2' via the inlet 11. Where the heat exchanger takes the form of some other kind of cooler or heater, the various media will be those needed for the cooler/heater concerned.

A design as above enables the upstream area of the heat exchanger to be made larger without the overall dimensions of the heat exchanger becoming larger. The upstream area is the area which the cooling/heating medium first encounters, i.e. the forward area of the heat exchanger in cases where it is fitted at the front behind the grille, e.g. on a truck. The upstream area is the most effective heat transfer area, since that is the area of greatest temperature difference between medium which is to be cooled/heated and the cooling/heating medium. For a given overall size of heat exchanger, the invention thus results in a more effective heat transfer.

What is stated above is merely an example by way of illustration and does not limit the scope of the invention. The scope of protection is only limited by the claims set out below. Thus the heat exchanger may take the form of a heat exchanger other than a water cooler for a vehicle, e.g. it may take the form of a charge air cooler or of a heat exchanger in the vehicle's air conditioning system. Nor is the invention limited to vehicles, as it may also be applied in, for example, passenger vehicles, construction machines and any other kind of vehicle desired, and also outside the vehicle sector, e.g. in air conditioning systems.